There are many patents showing hose couplings for terminating a hose of the type used for air brake pressure lines, gasoline line, water hoses, etc. However, in most cases those hose couplings which would be the most satisfactory are relatively expensive to manufacture. Therefor a less expensive type of hose coupling is often used which is not entirely satisfactory. One of the most common types of couplings is shown in U.S. Pat. No. 2,430,921 to Edelmann which includes a tubular nipple slidably received in the end of the hose and held thereon by a metal cup which is initially large enough to slide over the end of the hose easily but is subsequently crimped or spun inwardly against the hose to captivate it to the nipple. This type of coupling suffers from several disadvantages. In the first place, it is not entirely reliable because the process of crimping or spinning the cup onto the hose cannot achieve a precise pressure on the hose which is invariable from product to product. The type of metal used in the cup tends to vary in its physical characteristics, and this variation produces cups which when spun onto the hose can be embrittled, cracked in a manner that does'nt show in an inspection, and perhaps unable to maintain their newly crimped positions around the hose. Moreover, these cups are generally made of plated steel, and crimping or spinning of the cup tends to destroy the finish so that the cup is easily attacked by corrosive materials encountered during use of the hose, for instance, the salt spread on highways or acids contained in the atmosphere. Therefore, the stability of the shape of the deformed cup may become unpredictable, unstable and/or unreliable with the passage of time.
Moreover, when attached to a mating coupling this type of unit depends for its seal upon the deformation of the outer end of the tubular nipple. Therefore, once the unit has been coupled, it is no longer reliable to achieve a leak-proof connection if it is removed and reapplied a second time.
Efforts to overcome such disadvantages have often resulted in a complex and expensive coupling, for example such as is shown in U.S. Pat. No. 3,999,781 to Todd, which structure uses a large number of parts which require complicated machining. Another approach to attaching a coupling to a hose has been to place a ferrule around the outer surface of the hose and then jam a nipple into the hose which causes the hose to be driven radially outwardly into tight contact with the ferrule. This assembly, however, has certain disadvantages. One disadvantage is that when the nipple is driven into the hose, the nipple tends to drive it axially out of the ferrule so that the linear length of the engagement between the ferrule and the hose is uncertain. Another disadvantage is that this type of coupling provides no interengagement between the ferrule and the screw threaded fitting, whereby all of the strain tending to pull the hose out of the coupling must be borne by the barbs on the nipple. U.S. Pat. No. 3,262,721 to Knight is of this type.
The above disadvantages are obviated by the structure of U.S. Pat. No. 4,152,016 to Weinhold which shows a positive clamping means for clamping the hose onto the barbed nipple, which clamping means also has means which interengage with the threaded fitting and hold the fitting longitudinally to the hose, while allowing it to rotate with respect thereto, a separate annular seal also being provided between the nipple and the threaded fitting. However, this structure is still more complicated and expensive to manufacture then necessary, and provides a coupling whose outer diameter is unnecessarily bulky and subject to being snagged accidentally.
Copies of the four patents mentioned above are attached to this application in lieu of a prior art statement.